Fuel injection system



June 23, 1959 R. c. GROVES 5% FUEL INJECTION SYSTEM Filed July 11, 1956 4 Shee' tS-Sheet 1 INVENTOR f TTORNEY June 23, 1959 I R. c. GROVES 2,391,533

' FUEL INJECTION SYSTEM Filed July 11, 1956 4 Sheets-Sheet 2 INVENTOR Gag/g) ATTORNEY June 23, 1959 R.-C. GROVE-S FUEL INJECTION SYSTEM 4 sheds-sheer 3 Filed July '11, 1956 June 23, 1959 Filed July 11, 1956 R. C. GROVES FUEL INJECTION SYSTEM I 4 Sheets-Sheet 4 ill INVENTOR ATTORNEY nited Stats Patent 2 891533 Patented June 23,1959

FUEL lNJEfiTIQN SYSTEM Ronald C. Groves, Grammars, Micli., assignor ts Gem era! Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 11, 1956, Serial No. 597,237

2 Claims. (Cl; 123-140) The present invention" relates to internal combustion engines and more particularly to charge forming means for injecting metered quantities of fuelinto the charge for the engine cylinders.

In a so-called spark ignited engine a combustible charge of air and fuel is formed and then compressed in-t-he enginecylinders where it is .ignited. This charge may be formedby the induction air flowing through a carburetor having a venturi with a restricted throat therein. The fuel is aspirated froma jet located in the throat to mix Withthe charge as it flows through the venturi. The resultant charge of air and fuel is then distributed to the various engine cylinders by means of induction passages in an intake manifold. Such an arrangementworks satisfactorily and at the present time is almost universally employed on automotive engines. However, as the charge flows throughthe induction passages, the variations inthe shapes and sizes" thereof cause a nonuniformity of the charges aet-ually delivered to the engine cylinders. These inherent defects: are becoming more critical in the modern high compressionjengine and, accordingly, a considerable" amount of effort has been directed toward developing a; fuelinjeetionsystem that will accurately meter the fuel-flow and that will insure identical quantities of fuel to be injected into the individual charges in or immediately adjacent to the cylinders. However, so far, no fuel injection systems have found extensive use in automotive vehicles as they have not been capable of accurately meteringthe fuel and insuring each of the cylinders obtaining'identical charges.

It is now proposed to provide a fuel injection system that is adapted for use onautomotive enginesand that will insure each of the cylinders receiving identical changes. This is to be accomplished by providing a metering; assembly having a separate injector pump for each cylinder and a control unit that isresponsive to the fuel demandsoftheengine for controlling all of the injeetor pumps in unison to insure a uniformity of charging of thecylinders H I I V p Intli'e four sheets of drawings: I e

Figure 1 is a fragmentary;plan view of an engine emp'loyi ng a fuel injection-system embodying the present in-' vention; e H

Figure 2 is across-sectional view of the metering assemblyemployeddn theinjection system ofFigure l and taken alongthe linei2 2 of Figure l. 1 e V Figure 3 is a. cross sectional view taken substantially along the plane of lirie 33 i 'n Figure 2.

Figures 4, 5 and 6 are cross-sectional views of the control unit' in variousoperatingpositions. H e 7 Referring to the drawings in more detail the present invention may adapted for use in suitable internal combustion engine 12. For example, the engine 12 may be of the so-called V-type wherein the cylinders are arranged in a pair of an'gmsriy disposed banks 14. Cylinder heads 16' maybe provided for each bank 14 to close the upper ends of the cylinders and form combustion chambers- An induction system may be pfovide'din the space between the two banks I4'of cylinders. This system includes an intake ni'afiifold having an inlet with a throttle valve therein and a p'luiality' of induction passages that 2. communicate with the intake passages 18 in the cylinder heads 16. The flow of the charge into the combustion chambers may be timed: by the; intake? valves 20 that are actuated by the'engine'camsh'aft.

In order to form the combustible charge'of air andfuela fuel injection system 22 may be provided. for injecting metered quantities of fuel into: thecharges. T his system 22 includes low pressurefu'cl-supply means 24. an injector pump 26 andidrivevmeans 28 having a metering-control 30;ll1j66t0111i1168f32 and. injector nozzles 34.

The injector pump'26 includes a housing adapted'to be mounted on the front end of the cylinder block in the spacebetween thetwo banks 14; ofcylinders. The housing includes two banks 36.,of pumping assemblies 33so that .there is :a separate assembly for. each of the engine cylinders. The meteringcontrolfifly is disposed in the space between the. tWO. banks 36. and is 'op'erati'vely connect'ed to'the pumping? assemblies 378 by control racks 40: A pump camshaft. 42*rnay extendthe length of the hous-v ing at the intersection of the twobanks 36 so thatthe' cam followers 44 on the endsofpumping assemblies 38 may be, driventherefrom. The pump camshaft 42, is driven from theeng-ine camshaft by gearing 28 that will insure the pumping ass'enrbli'es138 being actuated in timed relation to-the cylinders; ,A' low pressure fuel manifold 46 extends down each ofthe banks 36so that a transfer pump 25 may supply fuel thereto under an adequate pres-. sure to insure fuel delivery to allof the pumping assemblies38. Although-the transfer pump, 25; may be' of any desired variety but in the present-instance it is a gear type pump and isv located at=theaft-end-iofthe housing: to be driven from the pump camshaft 42 at'engine. crankshaft speed. 7

Each of the injector assemblies e8 includes a bushing 47 that is secured in a passage 4 8 forming one of the banks 36. The bushing 47 includes anaxial passage 50 with a group of upper ports 52 disposed in a plane normal to the axis of the passageSO and a lower port 54 that is located some specific distance below the; plane of the upper ports 52. A plunger 56;is reeiprocably disposed in the axialpa'ssag-e 50-.- The-lower end of thep'lunger 56 includes the follower 44th'at-ridesona cam to be driven thereby. Apinion 58 on the plunger 56 engages a control rack 4-0 interconnected with the control'unit 30 so that the angular position of theplunger 56 will be set by the control unit 30'. The upper end' of the plunger 56} includes a head: 60 thaftiis separated from the main. body by an undercut62' that forms ahelical shoulder 64 on the main body of the plunger 56 The upper end of the passage 50 is closed bya cap 6 6-t0 form a discharge chamber 68. The cap 6 6 includesa pressure responsive check valve 70 that-interconnectsthe discharge chamber 68 with; theinjector lines 32 and injector nozzles 34. A drilled' passage through the plunger interconnects the undercut h e r s h mb z,

As the cam rotates and drives the plunger 56 upward the fuel in the chamber 68;W i11b6 discharged through all five of the ports 52 back into the fuel manifold 46 until the head 60 ofthe plunger 56 covers the top ports 52 and forces fuel downwardly through the drilled passage 72 into the space between the head and the helical shoulder formed. on the plungerbody by the undercut 62. When. this shoulder 64 closes the lower port 541 the fuel will be forced to. flow through the outlet valve 70 at the; top of the chamber 68 and-along the injector lines 32 and out of the injector nozzles34. This is the start of the injection and it will continue until the upper ports 52 are opened by the undercut 6;. Wli'enthis happens the valve 70 will close and fuel: will flow downwardly through the drilledipassage 72. and through the ports 52 into the fuel manifold 46. It may thus be seen that the effective length of the injector stroke will be determined by the distance between the point where helical edge 64 covers the lower port 54 and the point at which the undercut 62 exposes the upper ports 52. This distance is determined 'by the angular position of the plunger 56 as determined by the control racks 40 which are actuated by the control unit 30.

The control unit includes a pressure responsive bellows 74, a servo piston 76, a servo valve 78 for actuating said piston 76, and a walking beam 80 that interconnects all of these elements with each other.

The bellows 74 is a sealed unit disposed inside of a closed housing 82 which is interconnected with the induction system so as to be responsive to induction vacuum. A shaft 84 extends downwardly from the bellows 74 so that a spring 86 may act thereagainst. It will thus be seen that the lower end of the shaft 84- will assume some fixed position for any given vacuum. The servo valve 78 includes a barrel 88 having an axial passage 90 therethrough with an inlet port 92 which communicates with the engine lubrication system and a pair of control ports 94 and 96. The upper end 98 of the barrel 88 is threaded into the cover 100 to allow adjustment of its axial position. A plunger 102 is reciprocably disposed in the passage 90 with the lower end 104 thereof connected to one end of Walking beam 80. The upper end of the plunger 102 includes a pair of enlarged heads 104 and 106 that are positioned to cover both of the control ports 94 and 96. The inlet port 92 is connected to the lubrication system for the engine 12 so that it will receive a supply of servo fluid under pressure.

The piston 76 is reciprocably disposed in a cylinder 109 with the piston rod including a rack 110 that engages a pinion 112. The chamber 114 above the piston 76 is connected to one of the control ports 94 while the chamber 116 therebelow is connected 'to the other control port 96. As shown in copending application S. N. 638,102 Groves, filed February 4, 1957, the pinion 112 is mounted on a shaft 118 with pinion 119 on one outer end thereof that engages and actuates one of the control racks 40. The second control rack is actuated by the first through pinion 121 which engages both racks 40. In addition, a cam 120 is provided on the shaft to rotate therewith and engage the end of the walking beam. Thus, movement of the piston 76 will effect the position of this end of the beam 80 and cause it to pi"ot about the end of the bellows shaft 84 and thereby actuate the servo valve 78.

Operation of this injection system 22 may be summarized as follows: When the engine 12 is operating at a high fuel flow under stable conditions the control unit 30 will appear substantially as shown in Figure 2. The piston 76 will be at or near the top of its stroke and since a stable condition prevails, the heads 106 and 104 of servo plunger 102 will cover both control ports 94 and 96 and lock the piston 76 in a fixed position. The pinions 112 and 119 will have moved the control racks 40 to position the plungers 56 in the injector assemblies 38 for a long effective stroke to provide a large volume of fuel to match the large volume of air flow in some predetermined proportion.

If the throttle is closed or the load decreased the amount of the intake vacuum will increase and as a resuit the bellows '74 will lift the center of the walking beam 80. As best seen in Figure 4, this will lift the servo plunger 102 and open the upper control port 94. The lubrication oil from the engine may then flow into the upper piston chamber 114 and force the piston 76 downwardly. The oil in the lower piston chamber 116 will then flow through the lower control port 96 and be exhausted back to the engine lubrication system. Down ward travel of the piston 76 and its rack 110 will rotate the plnions 112 and 119 and the earn 120 to move the control racks 40 in a direction to decrease the effective stroke of the injector plungers 56. Downward travel of the piston 76 will rotate the cam 120 and allow one end of the beam to rise and the other end to descend until the servo plunger 102 again covers both control ports 94 and 96 and the piston 76'is again locked in position. As seen in Figure 5 when this stable condition is reached the injector plungers 56 will have been rotated to insure the desired air-fuel ratio. An adjustable stop 122 may be provided to limit the minimum effective strokes of the injector plungers 56 to insure an adequate supply of fuel at idle.

If the throttle valve is opened or the load increased the amount of the induction vacuum will decrease and the bellows 74 will lower the center of the walking beam 80 and lower the servo plunger 102 as seen in Figure 6. This will uncover the lower control port 96 and allow lubricant to flow into the lower chamber 116 and raise the piston 76. This will rotate the earn and move the control racks 40 to increase the effective stroke of the injector plungers 56. This movement will continue until the walking beam 80 moves the servo plunger 102 to cover the control ports 94 and 96.

It will thus be seen that by properly tailoring the contour of the surface of the cam 120, the control unit 30 will adjust the positions of injector plungers 56 to cause the volume of injected fuel to be in some predetermined proportion to the volume of the charge. The proportions of the air and fuel may be controlled by the axial position of the barrel 88.

I claim:

1. A fuel injection pump control mechanism for an internal combustion engine comprising a walking beam having three separate and longitudinally spaced fulcrums associated therewith, a pressure sensitive device responsive to the vacuum in the engine induction system operatively interconnected with a center fulcrum, a servo valve operatively interconnected with an end fulcrum, a servo piston controlled by said servo valve, means operatively interconnecting said servo piston and the fuel injection pump to control the quantity of fuel discharged from said pump in accordance with the position of said servo piston, and a cam member operatively interconnected with said servo piston and rotatable thereby, said cam member being operatively interconnected with said walking beam to provide the third fulcrum therefor and being adjustable in accordance with the position of said servo piston to vary the position of said walking beam and servo valve in proportion to the fuel being discharged from said pump.

2. A fuel injection pump control mechanism for an internal combustion engine comprising a walking beam having at least three separate, longitudinally spaced and adjustable fulcrums associated therewith, a pressure sensitive device responsive to the vacuum in the engine induction system operatively connected to said beam and providing one of said fulcrums, a servo valve operatively interconnected to said walking beam to provide another of said fulcrums, a servo piston controlled by said servo valve and adapted to control the quantity of fuel discharged from said pump in accordance with the position of said servo piston, a cam operatively connected with said servo piston and operatively interconnected with the walking beam to provide the third fulcrum therefor, said cam being adapted to neutralize the position of said servo valve to interrupt movement of the servo piston after said piston has been moved a predetermined amount due to actuation of the pressure sensitive device.

References Cited in the file of this patent UNITED STATES PATENTS 2,048,406 Olsen July 21, 1936 2,139,981 Sngihara Dec. 13, 1938 2,305,070 Butler et al Dec. 15, 1942 2,696,807 Iunge et a1. Dec. 14, 1954 2,719,517 Adler Oct. 4, 1955 

